Check if object is being drawn in the scene
It's hard to know if this can be a solution for you or not, but here's what I would try:

Use either Object Index or Material Index to create a pass that will be like a mask of the object's outline.

So for example, in Cycles if you create a material with a Pass Index of 1 (as is on this cube)...





Then you could set up your nodes to get a mask from that like so:



Note that since the monkey object in front of the cube does not have a Material Index of 1, it occludes the cube.

You can set this up using the File Output node so that this gets output separately from the main render as its own file:



Then you can use an external script (in Python perhaps) to batch scan your frames and return TRUE when white pixels are found, or FALSE when the frame is all black.

This is a very specific use case, so expect to have to do custom scripting.